Ergocalciferol, also known as vitamin D2 and nonspecifically calciferol, is a type of vitamin D found in food. It is used as a dietary supplement[ due to malabsorption or liver disease.][ It may also be used for hypocalcemia due to hypoparathyroidism.][ It is taken by mouth or via intramuscular.]
Excessive doses can result in vitamin D toxicity causing increased urine production, high blood pressure, kidney stones, kidney failure, muscle weakness, and constipation.[ Normal doses are safe in pregnancy.][ Food in which it is found include some mushrooms.]
Ergocalciferol was first described in 1936.[ In 2023, it was the 48th most commonly prescribed medication in the United States, with more than 13million prescriptions.]
Use
Ergocalciferol may be used as a vitamin D supplement, whereas cholecalciferol (vitamin D3) is produced naturally by the skin when exposed to ultraviolet light.[
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Mechanism
Ergocalciferol is a secosteroid formed by a photochemistry bond breaking of a steroid, specifically, by the action of ultraviolet light (UV-B or UV-C) on ergosterol, a form of provitamin D2.
Like cholecalciferol, ergocalciferol is inactive by itself. It requires two to become active: the first in the liver by CYP2R1 to form 25-hydroxyergocalciferol (ercalcidiol or 25-OH D2[
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Ergocalciferol and metabolites have lower affinity to the vitamin D-binding protein compared to the D3 counterparts. The binding affinity of ercalcitriol to the vitamin D receptor is similar to that of calcitriol.
Sources
Fungus, from USDA nutrient database (per 100g), D2 + D3:
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Mushrooms, Agaricus bisporus:
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raw portobello: 0.3 μg (10 IU); exposed to ultraviolet light: 11.2 μg (446 IU)
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raw crimini: 0.1 μg (3 IU); exposed to ultraviolet light: 31.9 μg (1276 IU)
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Shiitake:
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raw: Vitamin D (D2 + D3): 0.4 μg (18 IU)
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dried: Vitamin D (D2 + D3): 3.9 μg (154 IU)
Lichen
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Cladina arbuscula specimens grown under different natural conditions contain provitamin D2 and vitamin D2, ranges 89–146 and 0.22–0.55 μg/g dry matter respectively. They also contain vitamin D3 (range 0.67 to 2.04 μg/g) although provitamin D3 could not be detected. Vitamin D levels correlate positively with UV irradiation.
Plantae
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Alfalfa ( Medicago sativa subsp. sativa), shoot: 4.8 μg (192 IU) vitamin D2, 0.1 μg (4 IU) vitamin D3
Biosynthesis
The vitamin D2 content in mushrooms and C. arbuscula increase with exposure to ultraviolet light.[
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When fresh mushrooms or dried powders are purposely exposed to ultraviolet light, vitamin D2 levels can be concentrated to much higher levels.
Button mushrooms with enhanced vitamin D2 content produced this way functions similarly to a vitamin D2 supplement; both effectively improves vitamin D status.[
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Names
Viosterol, the name given to early preparations of irradiated ergosterol, is essentially synonymous with ergocalciferol.[See "Viosterol" and "Calciferol" at Merriam-Webster Medical Dictionary, e.g., and , accessed 10 July 2014.] However, currently, Viosterol is also the brand name for cholecalciferol (vitamin D3) in some countries.
Ergocalciferol is manufactured and sold under various brand names, including Deltalin (Eli Lilly and Company), Drisdol (Sanofi-Synthelabo), and Calcidol (Patrin Pharma).
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